1. Field of the Invention
The invention relates to an ink supplying device for supplying ink to a recording head which is used for an ink jet recording apparatus and relates to the ink jet recording apparatus having such an ink supplying device. More particularly, the invention relates to an ink jet recording apparatus having a tube for supplying ink from an ink tank to a recording head and relates to an ink jet recording method.
2. Related Background Art
Hitherto, in an ink jet recording apparatus for printing by reciprocating a recording head mounted on a carriage, it is necessary to increase a capacity of an ink tank in order to reduce an exchange frequency of the ink tank. However, according to a simple recording head integrated type, since inertia of the ink tank or the like mounted on the carriage increases, the ink tank is arranged at a position where it is not moved, a tube or the like is connected to the recording head on the carriage, and ink is supplied by using various pumps or the like. In the supply tube, in order to avoid a situation such that a pressure loss is increased in dependence on a bore of the tube, a viscosity, a density, and a flow velocity of the ink which flows, an ink supply amount lacks, and printing operation cannot be continued, it is necessary to set the bore to a larger value in order to decrease the pressure loss even at the time of the presumed maximum flow rate.
However, according to the conventional method of setting the tube bore at which the sufficient ink of the maximum supply amount can be supplied, the maximum ink pass amount of the supply tube increases remarkably in association with realization of a high printing speed of a printer and an increase in number of simultaneous discharge nozzles. Since the supply tube becomes thick, rigidity of the tube is high, malleability deteriorates, and it is necessary to increase a bending radius of the tube upon arrangement. It is difficult to miniaturize the apparatus. In an ink jet printer of the type such that the carriage is scanned and printing is performed, a fluctuation of the ink due to the carriage scan increases by an increase in amount of ink existing in the movable tube, and there is a problem such that a print variation is caused by a pressure fluctuation due to ink inertia.
The invention is made to solve the above problems and it is an object of the invention to provide an ink jet recording apparatus and its recording control method, in which the occurrence of a recording variation due to an increase in negative pressure in a supply tube can be prevented without increasing a bore of the supply tube.
The inventors of the present invention paid attention to the fact that in most of actual recording matters, print duties are low and the maximum ink flow rate is not always necessary. The minimum supply tube bore is set in accordance with an ink flow rate in which a use frequency of the print duty is high, and an amount of ink which flows is calculated every scan of target recording data. At the same time, the inventors found out the fact that if it is determined that the pressure loss is high and defective printing due to the lack of ink supply amount is caused on the basis of the ink viscosity calculated from ink temperature detecting means, by extending a discharge interval according to it, the ink supply amount is compensated, so that a constructing flow path such as a supply tube or the like can be miniaturized.
That is, according to the present invention, the above object is accomplished by an ink jet recording apparatus comprising: a recording head for discharging ink from a plurality of discharge ports and recording onto a recording medium; a carriage on which the recording head is mounted and which reciprocatively scans on the recording medium; recording medium conveying means for conveying the recording medium in the direction perpendicular to a scanning direction of the carriage by a predetermined distance each time the carriage reciprocatively scans on the recording medium; an ink tank mounted at a position where it does not exercise an influence on the reciprocative scan of the carriage and the conveyance of the recording medium by the recording medium conveying means; an ink supply tube for supplying the ink from the ink tank to the recording head; and control means for controlling an ink discharge state of the recording head on the basis of an image signal which is inputted from an upper apparatus, wherein the control means adjusts a scanning speed of the carriage so as to suppress an increase in negative pressure in the supply tube.
According to the ink jet recording apparatus of the invention, since the control means for controlling the scanning speed of the carriage so as to suppress the increase in negative pressure in the supply tube is provided, when the negative pressure in the supply tube rises, the scanning speed of the carriage is decreased and the amount of ink which is discharged from the recording head can be suppressed. Therefore, the occurrence of the recording variation due to the increase in negative pressure in the supply tube can be prevented without increasing the bore of the supply tube.
According to another aspect of the present invention, there is provided an ink jet recording apparatus comprising: a recording head for discharging ink from a plurality of discharge ports and recording onto a recording medium; a carriage on which the recording head is mounted and which reciprocatively scans on the recording medium; recording medium conveying means for conveying the recording medium in the direction perpendicular to a scanning direction of the carriage by a predetermined distance each time the carriage reciprocatively scans on the recording medium; an ink tank mounted at a position where it does not exercise an influence on the reciprocative scan of the carriage and the conveyance of the recording medium by the recording medium conveying means; an ink supply tube for supplying the ink from the ink tank to the recording head; and control means for controlling an ink discharge state of the recording head on the basis of an image signal which is inputted from an upper apparatus, wherein the control means adjusts a non-recording time as a time during which no ink is discharged from the recording head so as to recover a pressure in the supply tube.
According to further another aspect of the present invention, there is provided an ink jet recording apparatus comprising: a recording head for discharging ink from a plurality of discharge ports and recording onto a recording medium; a carriage on which the recording head is mounted and which reciprocatively scans on the recording medium; recording medium conveying means for conveying the recording medium in the direction perpendicular to a scanning direction of the carriage by a predetermined distance each time the carriage reciprocatively scans on the recording medium; an ink tank mounted at a position where it does not exercise an influence on the reciprocative scan of the carriage and the conveyance of the recording medium by the recording medium conveying means; an ink supply tube for supplying the ink from the ink tank to the recording head; and control means for controlling an ink discharge state of the recording head on the basis of an image signal which is inputted from an upper apparatus, wherein the control means adjusts the number of overlap recording scanning times of the carriage so as to recover a pressure in the supply tube.
According to the present invention, there is provided an ink jet recording method in a recording control method for an ink jet recording apparatus comprising: a recording head for discharging ink from a plurality of discharge ports and recording onto a recording medium; a carriage on which the recording head is mounted and which reciprocatively scans on the recording medium; recording medium conveying means for conveying the recording medium in the direction perpendicular to a scanning direction of the carriage by a predetermined distance each time the carriage reciprocatively scans on the recording medium; an ink tank mounted at a position where it does not exercise an influence on the reciprocative scan of the carriage and the conveyance of the recording medium by the recording medium conveying means; an ink supply tube for supplying the ink from the ink tank to the recording head; and control means for controlling an ink discharge state of the recording head on the basis of an image signal which is inputted from an upper apparatus, wherein the method has a step of reducing a scanning speed of the carriage when the number of dots (to be discharged) of the ink which is discharged from the recording head per unit time, in which such a number has been calculated from the image signal, is equal to or larger than a reference discharge number.
According to another aspect of the present invention, there is provided an ink jet recording method in a recording control method for an ink jet recording apparatus comprising: a recording head for discharging ink from a plurality of discharge ports and recording onto a recording medium; a carriage on which the recording head is mounted and which reciprocatively scans on the recording medium; recording medium conveying means for conveying the recording medium in the direction perpendicular to a scanning direction of the carriage by a predetermined distance each time the carriage reciprocatively scans on the recording medium; an ink tank mounted at a position where it does not exercise an influence on the reciprocative scan of the carriage and the conveyance of the recording medium by the recording medium conveying means; an ink supply tube for supplying the ink from the ink tank to the recording head; and control means for controlling an ink discharge state of the recording head on the basis of an image signal which is inputted from an upper apparatus, wherein the method has a step of extending a non-recording time as a time during which no ink is discharged from the recording head when the number of dots (to be discharged) of the ink which is discharged from the recording head per unit time, in which such a number has been calculated from the image signal, is equal to or larger than a reference discharge number.
According to still another aspect of the present invention, there is provided an ink jet recording method in a recording control method for an ink jet recording apparatus comprising: a recording head for discharging ink from a plurality of discharge ports and recording onto a recording medium; a carriage on which the recording head is mounted and which reciprocatively scans on the recording medium; recording medium conveying means for conveying the recording medium in the direction perpendicular to a scanning direction of the carriage by a predetermined distance each time the carriage reciprocatively scans on the recording medium; an ink tank mounted at a position where it does not exercise an influence on the reciprocative scan of the carriage and the conveyance of the recording medium by the recording medium conveying means; an ink supply tube for supplying the ink from the ink tank to the recording head; and control means for controlling an ink discharge state of the recording head on the basis of an image signal which is inputted from an upper apparatus, wherein the method has a step of increasing the number of overlap recording scanning times of the carriage when the number of dots (to be discharged) of the ink which is discharged from the recording head per unit time, in which such a number has been calculated from the image signal, is equal to or larger than a reference discharge number.